The present invention relates to a fluorescent or luminous composition. More particularly, the present invention relates to a fluorescent or luminous composition having both of color and fluorescence or luminescence, which is useful for preventing counterfeit when it is formulated to an ink, a filler, and a toner for printing or coating.
It is known that coating of powder surface with a film of other substance improves the quality of the powder or imparts multiplicity to the quality, and a variety of methods for achieving the purposes have been hitherto proposed.
Examples of known coating techniques of forming films on substrate surfaces for their protection or decoration include many methods, such as a coating method, a precipitating method, a sputtering, a vacuum deposition method, an electrodeposition method, and an anodic oxidation method. However, it is difficult to have a uniform thickness by the coating method or precipitating method, and it is also difficult to obtain a thick film by the sputtering or vacuum deposition method. Furthermore, the electrodeposition method and the anodic oxidation method possess a problem that these methods are difficult to apply to the treatment of powder because they use a substrate to be treated as an electrode.
With the progress in various technical fields, there is an increasing demand for a powder, especially a metal powder or metal compound powder, possessing a specific property, and a powder with combined functions having a property other than the properties inherent only in a powder, especially a metal powder or metal compound powder is desired.
For example, in a magnetic metal powder for use as a raw material for a magnetic color toner, the magnetic metal powder cannot be used if the color thereof remains as it is, although this does not arise a problem in conventional black magnetic toners. Any conventionally known coated powder obtained by forming a thin metal oxide film on the surface of a powder for the purpose of surface modification, such as the protection of the powder or the facilitation of mixing the powder with a synthetic resin or the like does not satisfy the new requirements in such fields. From this viewpoint, it is necessary to provide a powder having a novel constitution that is not seen in any conventional powder.
As a useful method for forming a metal oxide in order to provide a powder, especially a metal powder or metal compound powder having combined properties satisfying the above new requirements and capable of realizing combined functions, there is disclosed a powder having a metal oxide film of a uniform thickness of 0.01 to 20 xcexcm comprising a metal different from the metal constituting the base material of a metal or metal compound on the surface of the base material, the metal oxide film being formed by dispersing a metal powder or a metal compound powder in a metal alkoxide solution and hydrolyzing the metal alkoxide (JP-A-6-228604).
At the powder, when at least two layers of the above metal oxide film are formed, a special function can be imparted by controlling the thickness of each layer of the films. For example, when coating films having different refractive indexes are formed on the base material surface in a thickness corresponding to one-fourth the wavelength of an incident light, all the light is reflected. The application of this technique to a base material of a magnetic material, such as powder of a metal including iron, cobalt, nickel, etc., powder of an alloy thereof, or powder of iron nitride, can afford a magnetic powder for magnetic toner which reflects all the light and glitters with a white color. Furthermore, it is disclosed that a magnetic color toner is obtained by forming a colored layer on the powder and then a resin layer thereon (JP-A-7-90310).
Moreover, it was found that the control of the combination of the substances constituting the multilayered film and the thickness can adjust the waveform of interference of the reflected light at the multilayered film-coated powder, and there is disclosed a multilayered film having a stable color tone during a long period storage without using any dye or pigment (WO 96/28269).
The inventors have tried to develop a highly functional metal or metal compound powder by imparting another property other than the properties inherent in a metal or metal compound powder which is used as a base material, through the formation of a film of a metal oxide or a metal on the surface of a metal powder or a metal oxide powder.
In color printing or magnetic color printing for gift checks, ticket cards and the like, a special function for preventing the counterfeit other than visual or magnetic reading is required in addition to elegant coloring. For the purpose of answering such a trend, there is disclosed a color ink composition exhibiting an beautiful and stable color tone of blue, green, yellow or the like without using any dye or pigment through adjustment of the interference waveform of a reflected light at the above multilayered film, and having a function capable of enhancing the counterfeit-preventive effect of printed articles according to a mode other than visual or magnetic reading through the combined use of a reader for ultraviolet ray or infrared ray because of the existence of an interference reflection peak outside the visible light region besides the visible light region (JP-A-10-60350).
However, with the above color ink composition, an instrument for inspection is necessary because genuine/counterfeit is judged in combination with a reader for a reflected light of ultraviolet light or infrared light. It is inevitable to have a function which enables an easy genuine/counterfeit discrimination and further enhances the counterfeit-preventive effect of printed articles according to a new mode, and therefore, there exists a necessity of improvement.
Accordingly, an object of the present invention is to solve these problems, and to provide a fluorescent or luminous composition which not only is useful as an ink for color printing and coating of a monochromatic, beautiful and stable color tone, such as blue, green, yellow, or the like, a filler for papers or plastics, a coating material and an ink for high performance magnetic color printing, but also has a function enhancing a counterfeit-preventive effect of printed articles through enabling the genuine/counterfeit discrimination according to a convenient mode, for example, the irradiation with a fluorescent lamp in a room or a light source, such as ultraviolet lamp or infrared lamp, without using any new instrument for inspection.
Namely, the present invention relates to the following (1) to (10).
(1) A fluorescent or luminous composition, comprising a multilayered film-coated powder having at least two coating films on a base particle, and a fluorescent or luminous substance.
(2) The fluorescent or luminous composition according to the above (1), wherein at least one layer of the coating films contains the fluorescent or luminous substance.
(3) The fluorescent or luminous composition according to the above (1), wherein the multilayered film shows a light interference action.
(4) The fluorescent or luminous composition for counterfeit prevention according to the above (1), wherein the multilayered film shows a specific interference reflection peak or interference transmission bottom in a region besides the visible light region.
(5) The fluorescent or luminous composition according to the above (1), wherein the base particle is a magnetic particle.
(6) The fluorescent or luminous composition according to the above (1), which further contains a coloring agent.
(7) A genuine/counterfeit discrimination object, in which the fluorescent or luminous composition according to any one of the above (1) to (6) is adhered or contained.
(8) A genuine/counterfeit discrimination method, comprising recognizing fluorescence or luminescence by irradiating, with a light, the genuine/counterfeit discrimination object according to the above (7).
(9) The genuine/counterfeit discrimination method according to the above (8), wherein said method is combined with discrimination with at least one selected from magnetism, an electric field and an electron beam.
(10) Use of the fluorescent or luminous composition according to any one of the above (1) to (6) for genuine/counterfeit discrimination.